Induction heater for fiber processing roll

ABSTRACT

A fiber processing roll induction heater configuration which utilizes a secondary in the induction heating circuit which includes apertures therethrough to provide a desired temperature gradient along the rotating roll being heated.

United States Patent 6 [191 Brogden et al.

[ Nov. 13, 1973 INDUCTION HEATER FOR FIBER PROCESSING ROLL Inventors: Morris H. Brogden, Donelson,

Tenn.; Robert L. Geronime, Rosemount, Minn.

Assignee: Rosemount Inc., Minneapolis, Minn.

Filed: July 13, 1971 App]. No.: 162,140

11.5. C1 219/1061, 219/1041, 219/10.79 1nt. C1. .I H05b 5/00 Field of Search 219/1061, 10.63,

References Cited UNITED STATES PATENTS 8/1965 De La Bretoniere 219/1061 X o/vre ll 3,412,229 11/1968 Seagrave,.1r ..2|9/10.61

Primary Examiner-J. V. Truhe Assistant Examiner-Gale R. Peterson Attorney-Ralph L. Dugger et a1.

57 ABSTRACT A fiber processing roll induction heater configuration which utilizes a secondary in the induction heating circuit which includes apertures therethrough to provide a desired temperature gradient along the rotating, roll being heated.

11 Claims, 3 Drawing Figures PAIENTEDnnv 13 ms 3772.492

o/vre la INVFNTORS BY R OBERT L. GERON I ME A Tram 5V5 MORRIS H. BROGDEN INDUCTION HEATER FOR FIBER PROCESSING ROLL BACKGROUND OF THEINVENTION 1. Field of the Invention The present invention relates to heaters for processing'rolls used in fiber manufacture andthe like.

2. Prior Art 1 It has long been known that induction heating of processing rolls provides a satisfactory way for heating a rotating roll. For example, British Pat. No. 858,855 shows the basic design of an inductively heated roller or roll using a stationary winding which provides flux paths axially in the rotating roll for heating.

When this general heateris combined with tempera ture sensing apparatus for controlling the heater, a highly satisfactory form of heating the roll and maintaining a desired temperature, that is quickly responsive and efficient, is provided. However, it has been found that it is necessary and desirable to provide a means for supplying more or less heat to various sections of the roll so that a uniform temperature gradient is achieved along the axial length of the outer surface of the roll.

Two methods of accomplishing uniform heating are shown in U.S. Pat-Nos. 3,412,228 and 3,412,229. U.S. Pat. No. 3,412,229. discloses a conductive system of secondary rings spaced along the axial dimension of the roll. ln U.S. Pat. No. 3,412,228 a conductive sheath is placed in the interior of the roll which has varying thicknesses along the length of the roll to change the amount of heat inductively generated in the roll at different portions thereof. Designs such as those shown in U.S. Pat. Nos. 3,412,228 and 3,412,229 do provide a solution to the problem of having a desirable temperature gradient, but are not very desirable from a manufacturing standpoint since they add problems in forming and in cost of construction.

SUMMARY OF THE INVENTION The present invention discloses an improved means for providing a desired temperature gradient along the axial length of an outer surface of a rotating roll. A secondary conducting sheath is used on the interior of the roll. The sheath is formed separately from the roll, and can be fastened in place contiguous to the interior surface of the roll in any desired manner. The secondary sheath is provided with apertures of desired configuration and orientation to alter the heating characteristics of the sheath and the roll in the desired manner so that certain areas of the roll are heated more than others. One reason for varying the heat output along the roll axial length is to accommodate differences in heat dissipation of the roll.

1n the specific form shown, slots are utilized in the secondary sheath for providing these blocking apertures for the inducted secondary current. The slots are formed through the wall of a sleeve that is inserted into the roll and fastened into place.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a vertical sectional view through a typical heated roll assembly made according to the present invention;

FIG. 2 is a fragmentary perspective view of a roll liner or sleeve used with the roll of FIG. 1; and

FIG. 3 showsa modified configurationof a roll liner made according to the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT A rotating processing roll illustrated generally at 10 comprises a cup shaped rotating roll which has an annular wall outer shell member 11 and an outer end wall 12 both of ferromagnetic material. The roll is open at its other end. An annular flange 13 is fixed to the shell 11 adjacent the open end of the shell. The wall 12 has a hub 14 fixed thereto, which has a tapered bore, and is drivably fitted onto a power shaft 15. The shaft 15 has a tapered outer end 16 that fits 'into hub 14 and a nut 17 is threaded onto the shaft to hold the roll on the shaft. The shaft 15 is powered from a suitable source of power such as a motor to rotate the roll during processing operation.

The roll 10 is a heated roll used for processing synthetic fibers, or the like. The roll heating means comprises an inductive heating coil 20 which'is wound onto a high permeability coil carrier 21 that in turn is attached to a disc 23. The disc 23 in turn is attached a fixed frame 22. The disc 23 actually extends outwardly to adjacent the outer edge of the flange 13. All

of the interior structure in the roll including the coil 20,

the coil carrier 21, and the disc 23 and the frame 22 are stationary so that the roll rotates with respect to these units. The coil 21, which operates like a transformer winding, is wound helically around the coil carrier 21.

On the interior of the roll 10, a highly conductive sheath 25 is attached in heat conducting relationship to the inner surface of the roll shell 11. The sheath 25 acts as a transformer secondary and as shown is provided with apertures to control the temperature gradient on the roll. For example, there are axially extending, radially spaced slot type apertures 26 adjacent the open end of the roll, and also annularly extending slot type apertures 27 positioned more closely to the outer end wall 12 of the roll. I

The ends of coil 20 extend outwardly and are connected to AC. electric power through a controller, so that when the coil is powered a flux path is completed axially'along the coil carrier, through the closed end 12 of the rotating roll, and then through the shell 11 and back through the disc 23, which is also of high permeability material, to complete the flux path. This flux path is oriented in axial direction of the rotating roll and sets up a secondary current which flows circumferentially and which is highly concentrated in the conductive sheath 25. This secondary induced current flows annularly around the sheath (see FIG. 2 wherein the sheath is shown), and the current direction is shown by arrow 30. This current provides a resistance heating in the sheath 25 which acts as a primary source of heating for the rotating roll 10. The longitudinally extending apertures or slots 26, as shown in FIG. 2, and also in FIG. 1, interrupt or block secondary currents in the shell 25, thus causing less heat to be generated in the areas adjacent to the slot relative to the areas not so blocked by the slots. The axially extending slots affect the heating of the area of the sheath that is annularly equalize the temperature along the roll inner surface because of its ability to conduct heat easily. The sheath 25 is preferably made of a highly conductive material such as copper or aluminum.

The rotating roll tends to lose heat more rapidly at the closed end because of the wall 12, than it does at its open end, adjacent the disc 23, which is spaced from the roll itself. Therefore the quantity of heat supplied from the conductive sheath adjacent to the open end does not have to be as great as the heat supplied adjacent the closed end. The annularly extending slots 27 which are provided adjacent the closed end of the roll block the conduction of heat generated in sheath 25 adjacent this closed end of the roll and prevent the heat from being conducted readily toward the open end of the roll. Therefore by combining axially extending slots to minimize the heat initially generated in the sheath 25 adjacent the open end of the roll with annularly extending slots adjacent the closed end of the roll, the heat gradient along the axial length of the roll can be controlled quite readily. The width and length ofthe slots, as well as their spacing can be varied to suit the existing condition.

The sheath 25, as stated, may be made of aluminum or copper, and typically will be on the order of onesixteenth to one-fourth of an inch thick, and is uniform in thickness throughout its axial length. The slots or apertures can be formed by punching through the sheath after it is formed and before it is inserted into the roll. Then the sheath can be slipped into the interior of the roll, and can be held in place with retaining rings, screws, or by shrink fitting the sheath into the outer shell. it may also be staked in place or held in position by rolling a groove into the sheath material and the outer shell after the sheath has been slipped into the interior of the outer shell.

it has been found that a uniform wall thickness sheath without slots may result in a temperature gradient of to C along the axial dimension of the roll 10, when there is a 2 to 6 inch long outer roll surface and rotating at a surface velocity in the order of 30 feet per second. However, with the'slots or apertures 'properly oriented in the sheath this gradient may be reduced to approximately? C while still using the sheath with uniform wall thickness.

In general the axially oriented slots, or in other words the slots that extend in axial direction, cause a large change in the heat profile curve, since the slots extending in axial direction actually affect the application of power to the inner sheath and thus affect the generation of heat. By comparison, the annularly extending slots 27 do not greatly affect the power being supplied for heat generation in a significant manner, but do block thermal conductivity and thus affect the distribution of the heat to provide a slightly different but related type of control for the outer surface temperature of the roll.

Referring to FIG. 3, a modified sheath 32 is shown. The sheath 32 is mounted in the roll 10 in the same manner as before, but instead of using slots, the temperature regulating apertures in this instance comprise a series of drilled holes illustrated at 33, for example which are oriented closely together and are positioned to extend along an axial line. This is substantially equivalent to the slots 26. The different type of aperture gives a slightly different heat gradient, but accomplishes the same purposes. Likewise, apertures 34,

which comprise drilled holes arranged closely together along an annular line approximate the slots 27 which are annularly extending along the roll. Thus the use of holes, or slots, or various configured apertures is within the concept of the invention. l

The temperature profile along the roll surface thus can be selected as desired and achieved by forming holes into a sheath that is assembled into the interior of the roll. There is no need for complex costly arrangement such as depositing material of various thicknesses on the inner surface of the roll cavity.

The controller for the coil may be operated in response to a temperature sensor which senses the roll temperature. Thus a desired roll temperature can be maintained.

What is claimed is:

1. In a heated roll including an outer shell, means for rotating said shell about an axis, said shell forming an interior chamber, heating means on the interior of said chamber spaced from said shell, a unitary sheath member of conductive material on the interior of said shell in heat conducting relation thereto, and a plurality of apertures defined within said sheath member, said apertures being positioned to disturb normal heat patterns on said shell to provide the desired temperature profile at the outer surface of said shell along the axial length of said shell, said apertures being spaced from each other by portions of said sheath in both axial and annular directions so that said sheath provides for at least some conduction in both annular and axial directions along the entire axial length of said sheath.

2. The combination specified in claim 1 wherein said heating means is a stationary coil forming a flux path in axial direction of the shell, and said sheath having a secondary current induced therein, at least some of said apertures being positioned to block normal flow of induced current in said sheath.

3. The heated roll of claim 2 wherein said shell has one closed end and an open end, said coil extending .into said interiorchamber through said openend,

means adjacent said open end to complete said flux path through said shell, said' sheath extending substantially the entire axial length of said shell.

4. The heated roll of claim 3 wherein at least some of said apertures are arranged adjacent said open end to block normal flow 'of induced current in said sheath.

5. The heated roll of claim 2 wherein said shell has one closed end and an open end, and wherein at least some of said apertures are arranged adjacent the closed end to block thermal conduction in axial direction toward the open end and others of said apertures are arranged in axial direction adjacent said open end to block flow of induced current in said sheath adjacent said open end.

6. A heated roll construction including an outer shell, means for mounting and rotating said shell, said shell having an interior chamber, heating means on the interior of said chamber spaced from said shell comprising a stationary coil for generating a flux flowing in a path in axial direction along said shaft and through said shell, an annular sheath member of substantially uniform thickness in radial direction on the interior of said shell rotatable with said shell and in heat conducting relationship thereto and forming an induced current secondary, and a plurality of apertures defined within said sheath member, said apertures being spaced from each other in said sheath so that said sheath provides some heat conduction along its entire length, said apertures being positioned to affect the temperature gradient along the outer surface of said shell by controlling heat conduction and induced current flow in the sheath.

7. The combination as specified in claim 6 wherein at least some of said apertures are oriented to substantially block the induced current flow flowing in normal direction through said sheath in selected areas of said sheath, and others of said apertures are oriented in said sheath to substantially block heat conduction in axial direction only and do not substantially affect current flow in the normal direction of current flow through said sheath.

8. The combination as specified in claim 6 wherein at least some of said apertures comprise axially extending slots.

9. The combination as specified in claim 6 wherein at least some of said apertures are oriented in said sheath to substantially block heat conduction in axial direction only and do not substantially affect current flow in the normal direction of current flow through said sheath.

10. The combination as specified in claim 6 wherein at least some of said apertures comprise annularly extending slots.

11. The method of forming a shell assembly to be rotated about an axis parallel to a flux field to inductively heat said shell by induced currents, comprising the steps of forming a unitary annular sheath of highly conductive material, providing apertures through the sheath oriented to interrupt normal induced current and heat transfer paths, inserting the sheath into the shell, and fastening said sheath on the interior of said roll in heat conducting relation thereto.

jgggg UNITED STATES PATENT OFFICE.

CERTIFICATE OF CORRECTION Patent No. 3,777,492 Dated November 13, 1973 Inventor(s) Morris H. Brogden et al.

It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

rm Column 4, line 57, (Claim 6, 'line 2), after "shell" insert--about an axis--; Column 4, line 61, (Claim 6, line 6), take out "shaft" and insert--mounting means--. Column 6, line 17, (Claim 11, line 9), cancel "roll" and insert--shell--.

Signed and sealed this 23rd day of April 19713..

(SEAL) Attest:

EDx-JARD I-'E.FLLZTCH3IR J R. C MARSHALL DANN Attesting Officer Commissionerof Patents 23 3 3 6 UNITED STATES PATENT .OFFICE.

CERTIFICATE 0F CORRECTION Patent No. 3,772,492 Dated November 13, 1973 Inventor(s) Morris H. Brogden et a1.

It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

rm fiwlumn 4, line 57, (Claim 6, line 2) after "shell" insert--about an axis"; Column 4, line 61, (Claim 6, line 6), take Qut "shaft" and insert--mounting means--. Column 6, line 17, (Claim 11, line 9), cancel "roll" and insert--shell--.

Signed and. sealed this 23rd day of A ril'w'm.

(SEAL) Attest:

EDE-JARD I='I.FLLZIGEEEII'1,JR. C MARSHALL [DAIN Attesting Officer Commissioner of Patents 

1. In a heated roll including an outer shell, means for rotating said shell about an axis, said shell forming an interior chamber, heating means on the interior of said chamber spaced from said shell, a unitary sheath member of conductive material on the interior of sAid shell in heat conducting relation thereto, and a plurality of apertures defined within said sheath member, said apertures being positioned to disturb normal heat patterns on said shell to provide the desired temperature profile at the outer surface of said shell along the axial length of said shell, said apertures being spaced from each other by portions of said sheath in both axial and annular directions so that said sheath provides for at least some conduction in both annular and axial directions along the entire axial length of said sheath.
 2. The combination specified in claim 1 wherein said heating means is a stationary coil forming a flux path in axial direction of the shell, and said sheath having a secondary current induced therein, at least some of said apertures being positioned to block normal flow of induced current in said sheath.
 3. The heated roll of claim 2 wherein said shell has one closed end and an open end, said coil extending into said interior chamber through said open end, means adjacent said open end to complete said flux path through said shell, said sheath extending substantially the entire axial length of said shell.
 4. The heated roll of claim 3 wherein at least some of said apertures are arranged adjacent said open end to block normal flow of induced current in said sheath.
 5. The heated roll of claim 2 wherein said shell has one closed end and an open end, and wherein at least some of said apertures are arranged adjacent the closed end to block thermal conduction in axial direction toward the open end and others of said apertures are arranged in axial direction adjacent said open end to block flow of induced current in said sheath adjacent said open end.
 6. A heated roll construction including an outer shell, means for mounting and rotating said shell, said shell having an interior chamber, heating means on the interior of said chamber spaced from said shell comprising a stationary coil for generating a flux flowing in a path in axial direction along said shaft and through said shell, an annular sheath member of substantially uniform thickness in radial direction on the interior of said shell rotatable with said shell and in heat conducting relationship thereto and forming an induced current secondary, and a plurality of apertures defined within said sheath member, said apertures being spaced from each other in said sheath so that said sheath provides some heat conduction along its entire length, said apertures being positioned to affect the temperature gradient along the outer surface of said shell by controlling heat conduction and induced current flow in the sheath.
 7. The combination as specified in claim 6 wherein at least some of said apertures are oriented to substantially block the induced current flow flowing in normal direction through said sheath in selected areas of said sheath, and others of said apertures are oriented in said sheath to substantially block heat conduction in axial direction only and do not substantially affect current flow in the normal direction of current flow through said sheath.
 8. The combination as specified in claim 6 wherein at least some of said apertures comprise axially extending slots.
 9. The combination as specified in claim 6 wherein at least some of said apertures are oriented in said sheath to substantially block heat conduction in axial direction only and do not substantially affect current flow in the normal direction of current flow through said sheath.
 10. The combination as specified in claim 6 wherein at least some of said apertures comprise annularly extending slots.
 11. The method of forming a shell assembly to be rotated about an axis parallel to a flux field to inductively heat said shell by induced currents, comprising the steps of forming a unitary annular sheath of highly conductive material, providing apertures through the sheath oriented to interrupt normal induced current and heat transfer paths, inserting the sheath into the shell, and fastening said sheath on the interiOr of said roll in heat conducting relation thereto. 